The Yuan class submarines, also known as 039A, have been described as an important part of China's growing submarine threat. The first Yuan's photos started popping out in 2004 and it joined service in probably 2005 or 2006. The second Yuan's photos started coming out in 2007 and we saw a slew of photos in 2007 and early 2008. But just as we started to see a new variant, 039B, we stopped seeing pictures again. So, now we get a photo of what appears to be 3 Yuan and 1 039G in a flotilla. Each submarine flotilla has 4 submarines (I think). So, it appears that a fourth 039A hasn't joined service yet, because it would make sense for the first 4 039A to be in the same flotilla. Here is the photo.
It appears that this is a variant of 039G rather than 039G1 from the arrangement of the limber holes. Consider that all 3 039G was in East Sea Fleet, it makes sense that this flotilla is in 039A.
So, it definitely seems that 039As are in service and would be playing a big role in any kind of Taiwan scenario.